Split tileset artwork loading out of TileSet.

This simplifies terrain loading and allows for
non-square tiles in game.

The editor still relies on the old code for now.

OpenRA.Game/Graphics/Theater.cs

@@ -0,0 +1,73 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2013 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.IO;
+using System.Linq;
+using OpenRA.FileFormats;
+using OpenRA.FileFormats.Graphics;
+using OpenRA.Traits;
+
+namespace OpenRA.Graphics
+{
+	public class Theater
+	{
+		SheetBuilder sheetBuilder;
+		Dictionary<ushort, Sprite[]> templates;
+		Sprite missingTile;
+
+		Sprite[] LoadTemplate(string filename, string[] exts)
+		{
+			using (var s = FileSystem.OpenWithExts(filename, exts))
+			{
+				var t = new Terrain(s);
+				return t.TileBitmapBytes
+					.Select(b => b != null ? sheetBuilder.Add(b, new Size(t.Width, t.Height)) : null)
+					.ToArray();
+			}
+		}
+
+		public Theater(TileSet tileset)
+		{
+			var allocated = false;
+			Func<Sheet> allocate = () =>
+			{
+				if (allocated)
+					throw new SheetOverflowException("Terrain sheet overflow");
+				allocated = true;
+
+				// TODO: Use a fixed sheet size specified in the tileset yaml
+				return SheetBuilder.AllocateSheet();
+			};
+
+			templates = new Dictionary<ushort, Sprite[]>();
+			sheetBuilder = new SheetBuilder(SheetType.Indexed, allocate);
+			foreach (var t in tileset.Templates)
+				templates.Add(t.Value.Id, LoadTemplate(t.Value.Image, tileset.Extensions));
+
+			// 1x1px transparent tile
+			missingTile = sheetBuilder.Add(new byte[1], new Size(1, 1));
+		}
+
+		public Sprite TileSprite(TileReference<ushort, byte> r)
+		{
+			Sprite[] template;
+			if (templates.TryGetValue(r.type, out template))
+				if (template.Length > r.index && template[r.index] != null)
+					return template[r.index];
+
+			return missingTile;
+		}
+
+		public Sheet Sheet { get { return sheetBuilder.Current; } }
+	}
+}